High FOM PCF-SPR refractive index sensor based on MgF₂-Au double-layer films

Area of Science:

• Photonics
• Optical Sensing
• Plasmonics

Background:

• Surface Plasmon Resonance (SPR) sensors are crucial for detecting changes in refractive index (RI).
• Photonic Crystal Fibers (PCFs) offer unique light-confining properties for enhanced sensing.
• Optimizing SPR sensor performance requires careful design of the sensing structure and plasmonic materials.

Purpose of the Study:

• To design and analyze a simple twin-core D-shape photonic crystal fiber sensor for refractive index (RI) measurement.
• To investigate the enhancement of SPR effect using a twin-core D-shape structure.
• To improve sensor sensitivity and figure of merit (FOM) by employing a MgF2-Au dual-layer film.

Main Methods:

• Finite Element Method (FEM) was employed for numerical analysis of the sensor's properties.
• The sensor design incorporates a twin-core D-shape photonic crystal fiber.
• A dual-layer film of Magnesium Fluoride (MgF2) and Gold (Au) was integrated to optimize the SPR characteristics.

Main Results:

• The twin-core D-shape structure effectively enhances the SPR effect.
• The MgF2-Au dual-layer film successfully narrows the linewidth in the loss spectrum.
• Achieved maximum wavelength sensitivity of 62,000 nm/RIU, FOM of 1281 RIU⁻¹, and resolution of 1.61×10⁻⁶ within the RI range of 1.32-1.42.

Conclusions:

• The proposed twin-core D-shape PCF sensor demonstrates superior performance for RI sensing.
• The combination of the D-shape structure and dual-layer film significantly boosts sensor sensitivity and FOM.
• This sensor design holds potential for high-precision RI measurement applications.